A wide variety of energy absorbing apparatus are available for use in situations where it is desirable to absorb the energy of an impact.
For ease of reference only, the present invention will now be described with regard to roading applications, where impact of an erratic vehicle with a stationary object, (such as for example only: a wall, utility, pole or tree) can cause severe injury and/or death to occupants travelling in the vehicle. Similarly, vehicles that have been driven off course may be significantly slowed down by contact with an energy absorbing apparatus, reducing the danger when entering areas of risk, particularly at high speeds.
Vehicle collisions with stationary objects are a large contributor to deaths and serious injuries. To reduce the damage to occupants during a collision, a number of assemblies have been devised to absorb and/or transfer the energy from the impact.
It is well known to use containers filled with water or sand as energy absorbing devices between roadways and stationary objects. One of the major disadvantages of this system is that the devices are relatively heavy, and in the case of the water filled devices, often difficult to maintain.
It is also well known to use air tight containers to absorb impact energy. These are somewhat effective, however once the container has had an initial impact and the container shattered or broken, there is no further way that energy can continue to be absorbed. These containers are known to be used both on land and sea, however they are not particularly effective when receiving a high energy impact.
U.S. Pat. No. 5,123,775 describes an impact attenuator to absorb the impact of vehicular collisions. The device described in this patent includes a fibreglass shell which defines a cavity in the interior thereof. Housed within the cavity is a plurality of layers of empty aluminium beverage cans. Each layer consists of a plurality of cans stacked end to end in a number of columns in the direction of anticipated impact. Each of the layers is then separated by a cardboard divider to maintain separation between the layers, and the assembled cans are then surrounded by a burlap shroud before being encased within the fibreglass shell.
This assembly has a number of disadvantages. As the aluminium cans are stacked end to end within the layers, the device will only function at its most effective when the collision occurs in a direction which is head-on into the end of the cans. This limits the types of situation where this assembly can be used and also may increase risk to a vehicle occupant if the apparatus is impacted from the non-preferable angle. Additionally as the individual layers of cardboard and cans are not fixed together, the energy absorbed on impact is not readily transferred throughout all layers of the device, limiting the effectiveness of the entire device to absorb impact. This system is also fairly labour intensive to produce, as individual cans need to be correctly positioned within columns and then layers, with cardboard dividers. The can and cardboard interior needs to then be encased in a burlap sack, then inserted within a fibreglass shell, making the process of producing the assembly time consuming and labour intensive.
A number of other roading barriers are known, such as those constructed using tyres. One such longitudinal barrier is described in WO 03/097964. This patent specification describes a longitudinal barrier constructed from a plurality of tyres that are configured in a staggered brick type fashion or are stacked on top of each other to form columns. The tyres are held in position by a series of cables, wire rope, or stakes depending on the configuration of the tyres. One disadvantage with this system is that tyres solely absorb the impact of a vehicle. For example the energy of the impact is only transferred to horizontally adjacent tyres via upright supports (binding devices 16, 26 or 47) The binding devices have a small surface area so the transfer of force to a tyre is limited. This invention is also labour intensive as it requires holes 13 to be cut into the tyres, refer to FIGS. 1, 3 and 5. Once the tyres have had holes introduced to them, there is a reduction in the amount of energy that can be absorbed or transferred through the system, further reducing the effectiveness of the tyres in absorbing impact. The barrier of WO 03/097964 is also limited slightly in that it is not surrounded by an outer shell or casing. The addition of an outer casing or shell seals the air inside the barrier, providing further resistance when the barrier is absorbing an impact.
In summary, the problem with the prior art assemblies such as shown in U.S. Pat. No. 5,123,775 and WO 03/097964 is the fact the vehicle itself still has to absorb the majority of the force of impact, which cannot be transferred or absorbed by the assembly, for the reasons mentioned above. In the case of U.S. Pat. No. 5,123,755 the impact absorption efficiency is limited is by the aluminium cans not being connected to either each other or the layered cardboard. On impact, the cans may fall apart from each other once the fibreglass housing has been shattered, further increasing the energy that needs to be absorbed by the vehicle instead of the barrier. These problems occur due to both prior art assemblies relying on the resilience of the individual materials to absorb the majority of the impact. Each of the above assemblies are also potentially time consuming and labour intensive to manufacture on a large scale.
It would therefore be useful to have an assembly where the elements within the assembly are all interconnected in such a way, to increase the amount of energy that is absorbed and/or transferred to the assembly from an impacting vehicle, thereby decreasing the amount of force conveyed back to the occupants of the colliding vehicle. Additionally, it would also be an advantage to have an assembly that could be quickly and easily manufactured using readily available materials. It would be a further advantage to have an assembly that could be constructed in a range of shapes, such as; circular, square; a line, to suit a range of applications, without being expensive to construct.
Conventional energy absorbing apparatus and road barriers including those as described above only utilise a single type of energy absorbing element. It would also be useful if there could be provided an energy absorbing device which can utilise at least 2 types of energy absorbing elements.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.